1. Field of the Invention
The present invention relates to a helmet for protecting the head of a driver of a motorcycle, a four-wheeled vehicle, or the like.
2. Description of the Prior Art
Generally, as helmets for motorcycle and four-wheeled drivers there are known a full-face type helmet and a jet type helmet. Particularly, in the former, full-face type helmet, the helmet is fitted on the driver's head completely, so when a transparent shield for opening and closing a window opening formed on the front side is closed, the driver's head gets stuffy due to heat and the driver feels quite uncomfortable.
As a helmet of this type designed to prevent the driver's head from getting stuffy and hot by introducing air into the interior of the helmet, there has been proposed a full-face type helmet having an air inlet formed near the upper edge of the window opening to blow off air to the interior of the helmet. However, since the position of the said air inlet corresponds to the forehead portion, the helmet is apt to be broken by shock in the event the driver falls down. Besides, a certain opening area causes deterioration of strength. Thus, it is possible that this helmet will no longer fulfill the function as a protective helmet.
In view of the above situation the applicant in the present case has proposed as Japanese Utility Model Laid-Open No. 73624/86 a ventilating device capable of introducing the outside air into the interior of a helmet without deteriorating the protecting function and strength of the helmet. In the invention disclosed therein, a communication hole for introducing the outside air into the helmet body is formed so that it can be opened and closed to fulfill two functions, that is, introduction of the outside air and stop thereof.
For ventilating the interior of a helmet, not only the introduction of the outside air but also the discharge of the inside air is considered. In other words, the aforementioned invention has only one ventilating function and is difficult to be considered fully satisfactory.